Acoustic treatment/sound deadening for a VERY echo-y room?
First post here, please be gentle! If this is inappropriate or in the wrong forum, please let me know.
Okay, I'll try to be semi-brief here. I've been into AV stuff for a few decades but I've never really delved into this area. I have built a room that houses a 5.1 (well kinda 5.2ish, two subs that are using the same signal via splitter) setup. The room is rectangular, approximately 30' x 16' x 12' (tall). The walls are all plywood and drywall, the ceiling is all steel, and the floor is all dense rubber (horse stall mats, if you're familiar with them). There is almost nothing in this room other than gym equipment.
Now, as you can imagine, the amount of echo is INSANE in this room. The music sounds very odd and annoying as a result. So, I've been researching acoustic foam/panels to try to help and good lord, I have no idea what I'm doing. I've seen tons and tons of conflicting/confusing advice (usually trying to sell something). All kinds of debates on what material to use, how big it should be, where it should be placed, on and on and on.
Long story short, I'm looking for a resource that's trusted where I can understand the basics of what I need to do. Articles or youtube videos or whatever would be greatly appreciated. Or even just some basic no-BS information would be great. I have just moved, so budget is a huge concern, I really need bang for the buck here. I am extremely handy so that part is not a problem.
Much appreciated in advance!